No do not flush
If the leaves are yellowing from bottom to the top, what in the hell makes you think its light burn??
Also, its lack of nitrogen. Your plants are in the flowering stage therefore they're taking all the juices out of the leaves and putting them into your buds.
Your plant will continue to yellow unless you hit it with a little bit of nitrogen.
But its not that bad that its yellowing you'll be just fine.
Personally with CFL's I'd let my leaves yellow and die off, creating more light for the bud sites.
Dont listen to the people who are telling you "it may almost be done" lol
Pics would help clarify